Landslide activity in London Clay at Warden Point, Isle of Sheppey, SE England

Abstract

The Port of London Authority (PLA) has for many years maintained a radar station at Warden Point, Isle of Sheppey, on the south side of the Thames Estuary. Until 1991, the station was manned continuously, but at that time, the cliff edge encroached close to the (unmanned) radar building seaward of the main station, and when the radar antennae were moved to a site further inland (but still within the same small compound), the opportunity was taken to convert to wholly unmanned operation and to demolish the existing buildings. The aerial photographs in this photographic feature have been selected from a sortie by Commission Air made on 27 January 2011 at or around low tide, specifically to permit the foreshore and cliffs in the vicinity of Warden Point to be viewed in connection with the PLA’s continuing interest in the cliff retreat at this site. These photographs are reproduced by kind permission of the Port of London Authority, who hold the copyright. The radar station is situated close to a small hamlet that is affected by the retreat of the coastal cliffs, having lost its church (St James’s) in the 19th century. A pile of rubble on the foreshore may mark the eventual position of its remains. Figure 1 is a long distance view in a southerly direction from the start of the sequence showing Warden Point. An account of the landslides at this site has been given by Dixon & Bromhead (2002). Outcomes of that research included confirmation that there were low pore water pressures in the clay owing to undrained unloading, and added significantly to the stock of back analysed residual strengths. Fig. 1. General aerial view of Warden Point looking in a southerly direction. Figure reproduced with kind permission of Port of London …